Multi Junction Solar Cells Stacked with Transparent and Conductive Adhesive

We propose a polyimide transparent adhesive layer dispersed with In₂O₃-SnO₂ (ITO) conductive particles (polyimide-ITO) to be used in the mechanical stacking of solar cells. A 20-µm-thick polyimide-ITO layer had a high transmissivity from 78 to 80% for wavelengths ranging from 500 to 1000 nm and a low connecting resistivity of 2.3 Ω cm² at minimum. The fabrication of stacked cell consisting of a top hydrogenated amorphous silicon (a-Si:H) p-i-n cell and a bottom hetero-junction with an intrinsic thin-layer (HIT)-type silicon cell was demonstrated using an intermediate polyimide-ITO layer. A high open circuit voltage of 1.34 V was experimentally obtained. Simultaneous electric power generation from the top and bottom solar cells was achieved.